Indocyanine green-activated photodynamic therapy with diode laser eradicates Enterococcus faecalis in infected root...

The current endodontic disinfection techniques may be supplemented with photodynamic therapy (PDT), which is believed to eliminate intracanal bacteria more efficiently. This in vitro study aimed to assess the antimicrobial effectiveness of PDT using various photosensitizers, in conjunction with a near-infrared diode laser (810 nm wavelength), in the root canals of teeth infected with Enterococcus faecalis. This research is crucial for determining the optimal PDT method for eliminating E. faecalis, thereby enhancing the effectiveness of endodontic disinfection techniques.

This in vitro experimental study was conducted on 50 intact human maxillary first molars, which were decoronated, and palatal roots were instrumented to ISO size X5. After autoclaving, roots were inoculated with E. faecalis (ATCC 29212; 10⁸ CFU/mL) and incubated anaerobically for 72 h. The roots were randomly divided into five experimental groups: control (C), laser alone (L), PDT with indocyanine green (ICG), PDT with methylene blue (MB), and PDT with cetrimide (CT) 2%. Root canals were flushed with phosphate-buffered saline, and serial dilutions were plated on agar. Colony-forming units were counted after 48-h incubation. Data were analyzed using one-way analysis of variance followed by Tukey's post hoc test for pairwise comparisons. A significance level of P < 0.05 was considered.

PDT with ICG resulted in complete eradication of E. faecalis (0 CFU/mL), whereas PDT with MB and CT produced significant reductions (5.08 ± 0.2 and 5.55 ± 0.1 log₁₀ CFU/mL, respectively; P < 0.05). Laser alone reduced CFU/mL to 5.94 ± 0.07.

PDT with ICG and an 810 nm diode laser achieved complete eradication of E. faecalis, outperforming MB, CT, and laser alone. These results advocate for ICG-PDT as a potent adjunct in endodontic disinfection protocols.